As a light emitting material to be used in a light emitting layer of a light emitting device, a composition is known obtained by allowing a host material to be doped with a phosphorescence emitting compound showing light emission from the triplet excited state as a dopant.
As a basic property of a host material, it is important that the lowest triplet excitation energy (hereinafter, referred to as “T1 energy”) of the host material is high. As a host material having a relatively high T1 energy for a red phosphorescence emitting compound, there is suggested a copolymer (polymer compound) composed of a fluorene-2,7-diyl group and a 1,3-phenylene group having a specific substituent only at 5-position (International Publication WO 2007/133632).